The water table is so high in the New Orleans area that you can't really dig too deep before you hit water. (That's why their cemeteries have the burial vaults above ground.)
Even if there was a ladder, a sudden rain event could raise the water level high enough in the storm sewer that he could swim to the top rung.
I live in south central LA. I tell my relatives the water level is so high I can go fishing in my yard with a post hole digger :)
Thank you for explaining this,now that makes sense.